The characteristics of the microbiome in regard to developmental and postnatal exposure to environmental chemicals and the possible associations with markers of glucose metabolism abnormalities will be examined in >500 young adults, who are members of a unique birth cohort established in 1986-1987 at the Faroe Islands, a community with an unusually wide range of exposures to environmental chemicals. Cohort members will be invited at age 28 years for clinical examination, and a fecal sample will be obtained. Data on past chemical exposures, diet, medical history and other covariates were obtained at birth and at previous clinical examinations at ages 7, 14, and 22 years, in which 84%-90% of the cohort (N = 1,000) participated. The data include exposures to methylmercury, PCBs, DDE, and perfluorinated compounds. The clinical examination will include glucose tolerance test. The structure and function of the gut microbiome of these subjects will be assessed in a two-stage process. The microbes present in every sample will be determined by 16S rRNA gene sequencing, followed by deep metagenomic and metatranscriptomic sequencing on a subset of samples chosen to be maximally biologically informative. In combination with downstream statistical biomarker discovery, this will allow the determination of microbial clades, genes, pathways, or transcripts associated with early life chemical exposure and subsequent adult glucose tolerance.